1Jim Thomas - LBL

The STAR Heavy Flavor TrackerAn Update and Progress Report

Jim Thomas

Lawrence Berkeley National Laboratory

March 6th, 2012

2Jim Thomas - LBL

The Light Quark Program at RHIC is Compelling

Lattice results

Its hot

Its dense

and it flowsat the partonic scale

and , too!

Spectra

Vn

Jets & Rcp

The evidence for a low viscosity, strongly interacting QGP is overwhelming, especially after QM 2011 (v3 , vn wow …!!)

3Jim Thomas - LBL

Where do we go from here?

• The Beam Energy Scan has been and will continue to be extraordinarily productive

– Alexander Schmah “Elliptic Flow of Identified Particles in Au+Au Reactions at √sNN = 7.7-62.4 GeV” … a tour de force

• Heavy Flavor– Elliptic flow for Charm is the smoking gun for thermalization at RHIC

– Heavy Flavor energy loss … still a bit mysterious

– Clear separation of Charm and Beauty by the topological reconstruction of events will enable a new range of precision

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HFT Charm

Where does all the Charm go?

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Opening the Heavy Flavor Sector

• When RHIC turned on … Strange quarks were “heavy and exotic”– We built a Si vertex tracker to locate strange mesons and baryons

– This turned out to be too easy to do with the TPC, alone

– Kaons, Lambdas, Omegas, Phi and even the Cascade

– Cross sections, Flow, Raa and more

• Now we want to re-define “heavy and exotic” and go after the Charm quark– Some success already with non-photonic electrons (leptonic and semi-leptonic

decays)

– Topological reconstruction of open Charm is better. Requires a new high resolution Si detector.

• Of course, at the LHC the definition of “heavy and exotic” is quite different. The yield of charmed mesons is greatly enhanced and so they are not exotic. B decays may be “rare and exotic” for ALICE … but maybe not. s can do magical things ….

– Note that some success with Upsilon’s at RHIC. Upsilon suppression reported by STAR at QM 2011 using non-photonic electrons.

6Jim Thomas - LBL

The HFT – Signature Physics Measurements

• hello

DOE milestone for 2016: “Measure production rates, high pT spectra, and correlations in heavy-ion collisions at √sNN = 200 GeV for identified hadrons with heavy flavor valence quarks to constrain the mechanism for parton energy loss in the QGP.”

Charmed Hadron v2

using 200 GeV Au+Au minimum bias collisions (500M events)

Charm-quark flow

Thermalization

of light-quarks

Charm-quark does

not flow

Drag coefficients

7Jim Thomas - LBL

• Non-photonic electrons decayed

from charm and beauty hadrons

• At pT ≥ 6 GeV/c,

RAA(n.p.e.) ~ RAA(h±)

• A surprising result

The HFT – Heavy Quark Energy Loss

• Here is what we can do with the HFT using topological ID of open charm

RC

P

STAR PRL 98 (2007) 192301 and Erratum

8Jim Thomas - LBL

The HFT: The Challenge

The STAR HFT has the capability to reconstruct the displaced vertex of

D0 K(B.R 3.8%, c = 123 m) Λc Kp (B. R. 5.0%, c = 59.9 m)and more …

• Primary Challenges

– Neutral particle decay

– Proper lifetime, c, 123 m

– Find a common vertex away from the primary vertex

– Identify daughters, measure pT , and reconstruct the invariant mass

Topological Reconstruction of Open Charm

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The Heavy Flavor Tracker: Location inside the TPC

• hello

PXL IST SSD

TPC

4 m

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The HFT – The configuration

SSDIST

Pixel Detector

10

20

30

-30

-10

-20

0

Cen

timet

ers

Beampipe

• The HFT puts 4 layers of Silicon around the vertex

• Provides 8 m space point resolution @ 2.5 cm

• 30 m vertex resolution @ 1 GeV, 10 m @ 5 GeV

• Works at high rate (~ 800 Hz – 1K)

• Does topological reconstruction of open charm

• Will be ready for the 2014 run

11Jim Thomas - LBL

Tracking: Getting a Boost from the TPC

• The TPC provides good but not excellent resolution at the vertex and at other intermediate radii

~ 1 mm

• The TPC provides an excellent angular constraint on the path of a predicted track segment

– This is very powerful.

– It gives a parallel beam with the addition of MCS from the IFC

• The best thing we can do is to put a pin-hole in front of the parallel beam track from the TPC

– This is the goal for the Si trackers: SSD, IST, and PXL

• The SSD and IST do not need extreme resolution. Instead, the goal is to maintain the parallel beam and not let it spread out

– MCS limited

– The PXL does the rest of the work

TPC

MCS Cone

VTX

The Gift of the TPC

OFC

IFC

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The performance of the TPC acting alone

• The performance of the TPC acting alone depends on the integration time of the PXL chip

P(good association) = 1 / (1+S) where S = 2 x y

Integration Time (sec)

Sin

gle

Laye

r E

ffici

ency

The purpose of intermediate tracking layers is to make 55% go up to ~100%

Note that the hard work gets done at PXL layer 2. This is a surprise.

13Jim Thomas - LBL

The performance of the TPC + SSD + IST

• The performance of the TPC + SSD or TPC + IST acting together depends on the integration time of the PXL chip … but overall the performance is very good

P(good association) = 1 / (1+S) where S = 2 x y

Integration Time (sec)

Sin

gle

Laye

r E

ffici

ency

Random errors only included in hand calculations and in GEANT/ITTF simulations

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The HFT – Pixel Technology

• Unique Features– 20.7 x 20.7 m pixels

– 100-200 sec integration time

– 436 M pixels

– 0.37% X/X0 per layer

– Install and Replace in 8 hours

• News– Change in process:

now using 400 cm moderate Resistivity Si

– Depletion voltage ~1V

– Better signal to noise and higher radiation tolerance >300 kRad, 1014 n/cm2

– Don’t have to replace the detector every year

Now using high resistivity Si

which allows for a biased

depletion region (previously

relied upon diffusion to collect

the charge)

22 cm

14 cm

8 cm

2.5 cm

.

HFT Si

SSD

IST

PXL2

PXL1

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Smart Pixels make the HFT unique

High efficiency detector wants high resistivity Si, CMOS cheap,

Smart electronics wants low resistivity Si for logic circuits

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Exploded view of the HFT inside the TPC

TPC Volume

OFCOuter Field Cage

IFCInner Field Cage

SSD

IST

PXL

FGT

HFT

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The “cone” assembly is removable (annually)

Forward GEM Tracker

Silicon Strip Detector(IST and HFT underneath)

Mechanics and electronics to support the HFT are underneath

4.2 Meters

~ 1 Meter

The SSD: 20 ladders located at a radius of 22 cm

Double sided Si strips, 95 m pitch, 4 cm long, crossed at 35 mrad

The electronics on each end of the ladder are to be upgraded

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The Old Silicon Strip Detector

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SSD Electronics

• New Ladder Card (left)

• Large FPGA on board

• Associated RDO in development

• Prototypes exist, moving to pre-production phase

• Trying to make it all fit

Goal: DAQ rate from 200 Hz 1 kHz

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Cone Installation

Cones installed Fall 2012

Shroud and OSC in place

Length ~4 m, Radius ~90 cm

SSD will sit on OSC

20 refurbished ladders around the circumference

Al mylar wrap covers the region over the SSD and between the shrouds

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Exploded view of the HFT inside the TPC

TPC Volume

OFCOuter Field Cage

IFCInner Field Cage

SSD

IST

PXL

FGT

HFT

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Prototype IST Staves (January 2012)

24 Staves at 14 cm radius

Intermediate between TPC/SSD and PXL

Prototype with Si modules and APV readout chips

Wire bonding is a success

Readout and electronics very similar to FGT

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• -1 ≤ Eta ≤ 1, full Phi coverage (TPC coverage)

• ≤ 30 µm DCA pointing resolution required for 750 MeV/c kaon– Two or more layers with a separation of > 5 cm.

– Pixel size of ≤ 30 µm

– Radiation length as low as possible but should be ≤ 0.5% / layer (including support structure). The goal is 0.37% / layer

• Integration time of < 200 μs

• Sensor efficiency ≥ 99% with accidental rate ≤ 10-4.

• Survive radiation environment.

• Air cooling

• Thinned silicon sensors (50 μm thickness)

• MAPS (Monolithic Active Pixel Sensor) pixel technology– Sensor power dissipation ~170 mW/cm2

– Sensor integration time < 200 μs (L=8×1027)

• Quick extraction and detector replacement (1 day)

PXL Requirements and Design ChoicesR

equi

rem

ents

Des

ign

Cho

ices

24Jim Thomas - LBL

Pixel support structure near the vertex

2.5 cm radius

8 cm radius

Inner layer

Outer layer

End view

Carbon fiber support beams

(green)

Two “D” sectors form the heart of the PXL detector. The two halves separate in order to allow for easy access, removal and repair.

25Jim Thomas - LBL

Hinge detail

• Parallelogram hinges support the two detector halves while sliding

• Cam and follower controls the opening of the hinges during insertion and extraction

• Detector support transfers to kinematic dock when positioned at the operating location

pixel support hinges

cam followers and linear camslide rails

sliding carriage

Reason for no bottom

Beam Pipe support…

kinematic dock

26Jim Thomas - LBL

HFT PXL status – fabrication and tooling

27Jim Thomas - LBL

Recent Progress – on many different scales

• PXL Insertion and Test Bed for installing the PXL detector into STAR

– Most Al parts become C fiber in the real thing

• A Hallmark of LBL Instrumentation is that things get tested before they are installed

• PXL Ladder “Cable” 2.5 cm by 30 cm

– Chips will go on lower 20 cm portion

– Prototype in Cu

– Final in Al to lower mass of ladder

28Jim Thomas - LBL

The PXL Engineering Run (Run 13)

• We are planning on a partial installation of PXL ladders for Run 13

– No SSD

– No IST

• Primarily an engineering run to test the PXL electronics and mechanics

– Some physics may be possible

– less efficient

Mercedes

Patch

Joined

Patch

29Jim Thomas - LBL

• D0 simulations by Jonathan Bouchet

• D0 input– 50k D0

– 0 < pT < 10

– -3 < < 3

– Basic cuts (pT > 0.1, < 1 ) 13K survive

• D0 output– Mercedes

970 events

– Joined 333 events

30Jim Thomas - LBL

Run 13 Engineering Run – Prospects for Physics

• D0 acceptance as a function of pT and patch geometry

• Overall breakdown and summary of acceptance

• Note: this does not include TPC tracking inefficiency nor pT dependent software cuts on the kinematics of the D0 … so the real world will be even more difficult

31Jim Thomas - LBL

PXL Detector Characteristics

Pointing resolution (12 19 GeV/pc) m

Layers Layer 1 at 2.5 cm radius

Layer 2 at 8 cm radius

Pixel size 20.7 m X 20.7 m

Hit resolution 6 m

Position stability 6 m rms (20 m envelope)

Radiation length per layer X/X0 = 0.37%

Number of pixels 356 M

Integration time (affects pileup) 185.6 s

Radiation environment 20 to 90 kRad

2*1011 to 1012 1MeV n eq/cm2

Rapid detector replacement ~ 1 day

356 M pixels on ~0.16 m2 of Silicon!

32Jim Thomas - LBL

Summary

• The HFT will explore the Charm sector at RHIC

• We will do direct topological reconstruction of Charm

• Our measurements will be unique at RHIC

• The key measurements include– V2

– Energy Loss

– Charm Spectra, RAA & Rcp

– Vector mesons

– Angular Correlations

• The technology is available on an appropriate schedule

33Jim Thomas - LBL

Backup Slides

34Jim Thomas - LBL

FY09 FY10 FY11 FY12 FY13 FY14 FY15

HFT Construction

HFTOperation

MTDConstruction

MTDOperation

HLT Development

HLT Operation

Finish HFT in time for the 2014 run

Finish MTD project by Mar, 2014 and make 80% of the full system ready for year 2014 run

HLT is seeking funds but is projected to be under development through FY15,

and will be available for physics at all times

Three STAR Upgrade Projects

35Jim Thomas - LBL

Radiation Load expected in 2014

Radcm 2.5 2.5 14.0 22.0 2.5 2.5 14 22

# of wks

Physkrad

Phys+ UPC krad

Physkrad

Physkrad

Ramp and Totalkrad

Ramp and Total n/cm2

Ramp and Total krad

Ramp and Total krad

200 GeV

Au + Au Max 12 28.3 59.8 0.9 0.4 88.0 1.1E+12 1.8 0.7

Au + Au Min

12 5.3 11.3 0.2 0.1 16.6 0.2E+12 0.3 0.1

500 GeV

p + p Max 12 133.3 133.3 4.3 1.7 266.7 5.3E+12 8.5 3.4

p + pMin 12 28.9 28.9 0.9 0.4 57.8 1.1E+12 1.8 0.7

36Jim Thomas - LBL

Efficiency Calculations in a high hit density environment

The probability of associating the right hit with the right track on the first pass through the reconstruction code is:

P(good association) = 1 / (1+S)

where S = 2 x y

P(bad association) = (1 – Efficiency) = S / ( 1 + S )

and when S is small

P(bad association) 2 x y

x is the convolution of the detector resolution and the projected track error in the ‘x’ direction, and is the density of hits.

The largest errors dominates the sum

x = ( 2xp + 2

xd )

y = ( 2yp + 2

yd )

Asymmetric pointing resolutions are very inefficient … try to avoid it

37Jim Thomas - LBL

TPC Pointing at the PXL Detector

• The TPC pointing resolution on the outer surface of the PXL Detector is greater than 1 mm … but lets calculate what the TPC can do alone

– Assume the new radial location at 8.0 cm for PXL-2, with 9 m detector resolution in each pixel layer and a 200 sec detector

– Notice that the pointing resolution on PXL-1 is very good even though the TPC pointing resolution on PXL-2 is not so good

• The probability of a good hit association on the first pass– 55% on PXL2

– 95% on PXL1

Radius PointResOn(R-)

PointResOn(Z)

Hit Density

8.0 cm 1.4 mm 1.5 mm 6.0

2.5 cm 90 m 110 m 61.5

This is a surprise: The hard work gets done at 8 cm!

The purpose of the intermediate tracking layers is to make 55% go up to ~100%

All values quoted for mid-rapidity Kaons at 750 MeV/c

38Jim Thomas - LBL

• Does charm flow hydrodynamically?– Heavy Flavor Tracker: unique access to low-pT fully reconstructed charm

• Are charmed hadrons produced via coalescence?– Heavy Flavor Tracker: unique access to charm baryons– Would force a significant reinterpretation of non-photonic electron RAA

• Muon Telescope Detector: precision measurements of J/ψ flow

Properties of the sQGP

39Jim Thomas - LBL

Rapid Insertion

During this operation the PXL box rests on two 6 inch aluminum box beams. These beams are supported independent of walking platform

Each half of the PXL detector is supported on two round slide rails both in the PXL storage box and in the MSC.In this procedure the box most be accurately moved into position to align the slide rails of the box with the rails in the MSC

Up dated, includes measurement tool for checking alignment of two rail systems and instructions

40Jim Thomas - LBL

Calculating the Performance of the Detector

• Billoir invented a matrix method for evaluating the performance of a detector system including MCS and dE/dx

– NIM 225 (1984) 352.

• The ‘Information Matrices’ used by Billoir are the inverse of the more commonly used covariance matrices

– thus, ’s are propagated through the system

• The calculations can be done by ‘hand’ or by ‘machine’ (with chains)

• STAR ITTF ‘machine’ uses a similar method (aka a Kalman Filter)– The ‘hand calculations’ go outside-in

– STAR Software goes outside-in and then inside-out, and averages the results, plus follows trees of candidate tracks. It is ‘smart’ software.

MCS D M MCS D M MCS

41Jim Thomas - LBL

Hand Calculations .vs. GEANT & ITTF

- - - - PXL stand alone configuration

Paper Proposal configuration

GEANT & ITTF adjusted to have the correct weights on PXL

layers

Updated configuration … no significant changes in pointing at

VTX

TPC alone

Full System

42Jim Thomas - LBL

Flow: Probing Thermalization of the Medium

py

)(tan,2cos 12

x

y

p

pv

Coordinate space: initial asymmetry

Momentum space: final asymmetry

pxx

y

Semiperipheral collisions

Signals early equilibration (teq 0.6 fm/c)

43Jim Thomas - LBL

Flow: Constituent Quark Number Scaling

In the recombination regime, meson and baryon v2 can be obtained from the quark v2 :

2 2 2 2v22

v3

v3v Btt

q tM q tp ppp

44Jim Thomas - LBL

Scaling as a Function of (mT – m0)

• The light quark sector scales beautifully with v2/nq .vs. (mT – m0)/nq

– Note that pT < 1 GeV always did scale !

• The strange quark sector also scales with <v2> and the scaling holds at all centralities

• Even the meson

V2 /

nq

Does it work in the Charm Sector?

A strong test of the theoryYuting Bai, QM 2006 for the STAR Collaboration

STAR Preliminary work by Yan Lu

45Jim Thomas - LBL

Baryons vs. mesons

• Coalescence and fragmentation conspire at intermediate pT to give constituent quark number scaling and Baryon-Meson differences.

• Coalescence and fragmentation of charm quarks is different than for light quarks … so it is a strong test of the theory

• Coalescence of light quarks implies deconfinement and thermalization prior to hadronization

• How do baryons and mesons behave in the Charm sector?

• The Λc will be a fascinating test … and we might be able to do it with the HFT via Λc / D

46Jim Thomas - LBL

“Heavy Flavor” is the next frontier at RHIC

• A low viscosity, sQGP is the universally accepted hypothesis

• The next step in confirming this hypothesis is the proof of thermalization of the light quarks in RHIC collisions

• The key element in proving this assertion is to observe the flow of charm … because charm and beauty are unique in their mass structure

• If heavy quarks flow– frequent interactions among all quarks

– light quarks (u,d,s) likely to be thermalized

Current quark: a bare quark whose mass is due to electroweak symmetry breaking

Constituent quark: a bare quark that has been dressed by fluctuations in the QCD sea

47Jim Thomas - LBL

Hints of Elliptic Flow with Charm

Shingo Sakai, QM 2006 for the PHENIX Collaboration

• D e +X

Single electron spectra from PHENIX show hints of elliptic flow

Is it charm or beauty?

• The HFT will cut out large photonic backgrounds:

e+e-

and reduce other large stat. and systematic uncertainties

• STAR can make this measurement with 50 M Au+Au events in the HFT

• Smoking gun for thermalization at RHIC!

Better if we can do direct topological identification of Charm

48Jim Thomas - LBL

Heavy Flavor Energy Loss … RAA for Charm

• Heavy Flavor energy loss is an unsolved problem

– Gluon density ~ 1000 expected from light quark data

– Better agreement with the addition of inelastic E loss

– Good agreement only if they ignore Beauty …

• Beauty dominates single electron spectra above 5 GeV

• We can separate the Charm and Beauty by the direct topological identification of Charm

Theory from Wicks et al. nucl-th/0512076v2

Where is the contribution from Beauty?

49Jim Thomas - LBL

A Rich Physics Program

• There is a rich physics program when all of the STAR physics detectors are working together

– Flow in the Charm sector

– dE/dx in the Charm sector

– Recombination and RAA in the Charm sector

– Vector Mesons

– Charm Angular Correlations

– non-photonic electrons

– …

50Jim Thomas - LBL

The Simplest ‘Simulation’ – basic performance check

• Study the last two layers of the system with basic telescope equations with MCS

– PXL 1 and PXL 2 alone ( no beam pipe )

– Give them 9 m resolution

0

( / )13.6mcs

MeV c x

p X

2 22 2 2 22 11 2 2 1

2 2

2 1sin ( )mcs rr r

r r

hh

• In the critical region for Kaons from D0 decay, 750 MeV to 1 GeV, the PXL single track pointing resolution is predicted to be 20-30 m … which is sufficient to pick out a D0 with c = 125 m

• The system (and especially the PXL detector) is operating at the MCS limit

• In principle, the full detector can be analyzed 2 layers at a time …

TPC alone

PXL alone

51Jim Thomas - LBL

– Goal: graded resolution and high efficiency from the outside in

– TPC – SSD – IST – PXL

– TPC pointing resolution at the SSD is ~ 1 mm

– SSD pointing at the IST is ~ 400 m (200 x 800)

– IST pointing at PXL 2 is ~ 400 m (200 x 800)

– PXL 2 pointing at PXL1 is ~ 125 m (90 x 175 )

– PXL1 pointing at the VTX is ~ 40 m (Kaon at 750 MeV)

Overview & Goals for Si Detectors Inside the TPC

The challenge is to find tracks in a high density environment with high efficiency because a D0 needs single track 2

~ 50 cm

52Jim Thomas - LBL

Graded Resolution from the Outside In

• A PXL detector requires external tracking to be a success– The TPC and intermediate tracking provide graded resolution from the

outside-in• The intermediate layers form the elements of a ‘hit finder’

– The spectral resolution is provided by the PXL layers• The next step is to ensure that the hit finding can be done

efficiently at every layer in a high hit density environment

TPCvtx

PXL alone

TPCSSDSSDISTISTPXL2PXL2PXL1PXL1VTX

53Jim Thomas - LBL

Central Collisions: Density of hits on the Detectors

dN dN d

dz d dz

2 2

1( , )

dr z

dz r z

where

22

1 700( ) 17.8

2 2

dN dNCentral cm

dA dz r r

Au+Au Luminosity (RHIC-II) 80 x 1026 cm-2s-1

dn/d (Central) 700 dn/d (MinBias) 170 MinBias cross section 10 barns MinBias collision rate (RHIC-II) 80 kHz Interaction diamond size, σ 15 cm Integration time for Pixel Chips 200 sec

Radius Simple Formula|| = 0

|| < 0.2 || < 1.0

PXL 1 2.5 cm 17.8 cm-2 19.0 cm-2 15.0 cm-2

PXL 2 8.0 cm 1.7 cm-2 1.8 cm-2 1.5 cm-2

IST 14.0 cm 0.57 cm-2 0.66 cm-2 0.52 cm-2

SSD 23.0 cm 0.21 cm-2 0.23 cm-2 0.19 cm-2

The density of hits is not large compared to the number of pixels on each layer. The challenge, instead, is for tracking to find the good hits in this dense environment.

Slightly

conservative

numbers

100,000

pixels cm-2

54Jim Thomas - LBL

MinBias Pileup – The PXL Layers Integrate over Time

A full study of the integrated hit loading on the PIXEL detector includes the associated pileup due to minBias Au-Au collisions and the integration time of the detector.

2022

00

1 1( , , , )

2 ( )2

za

a

dN dN dMinBias z r ZDC e dz

dA d r d z z

2022

02 20

2720 1 1( , , , )

2 2 ( )

za

a

dNMinBias z r e dz

dA r r z z

PIXEL-1 Inner Layer

PIXEL-2 Outer Layer

Radius 2.5 cm 8.0 cm Central collision hit density 17.8 cm-2 1.7 cm-2

Integrated MinBias collisions (pileup) 23.5 cm-2 4.2 cm-2

UPC electrons 19.9 cm-2 0.1 cm-2

Totals 61.2 cm-2 6.0 cm-2

Pileup is the bigger challenge

Integrate over time and interaction diamond

200 sec

Not insignificant

55Jim Thomas - LBL

A Quick Note About Absolute Efficiencies

• The previously quoted efficiencies do not include the geometric acceptance of the detectors

• The TPC has an approximately 90% geometric acceptance due to sector boundaries and sector gaps

– In addition, the TPC has an additional ~90% efficiency factor at RHIC II luminosities … this is a software and tracking issue due to the large multiplicity of tracks

• The SSD has an approximately 90% geometric acceptance due to areas where the crossed strips don’t achieve full coverage

• All ‘new’ detectors are assumed to have 100% geometric acceptance

• Efficiency from the previous slide– 0.98 x 0.98 x 0.93 x 0.94 = 0.84

• Geometric acceptance and TPC track finding efficiencies– 0.9 x 0.9 x 0.9 = 0.73 In this example Total = 0.61

56Jim Thomas - LBL

Single Track Efficiencies – Hand Calc .vs. ITTF

The efficiency for finding tracks in central Au+Au collisions in the STAR TPC and the HFT. Finite acceptance effects for the TPC and SSD are included in the simulations. The quoted efficiency from GEANT/ITTF is for || < 1.0 and for tracks coming from the primary vertex with |vz| < 5 cm.

Hand Calculations

Hand calculations assume the acceptance is flat in pT and assume a single track at = 0.5

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D0 Reconstruction Efficiencies Compared

Geant/ITTF

• The predicted absolute efficiency of the HFT detector. – The red squares show the efficiency for finding the D0 meson with the full set

of Geant/ITTF techniques.

• The green line shows the D0 efficiency predicted by the Geant/ITTF single particle efficiencies

• The blue line shows the D0 efficiency predicted by the hand calculations– Single track efficiencies for the kaon and pion are integrated over the Lorentz

kinematics of the daughter particles to predict the D0 efficiency

• Hand Calculation give guidance … but more complex questions should be answered by the full suite of tools available to Geant/ITTF

Hand Calculations

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A Robust Design

There is a rich physics program that can be addressed with the HFT in STAR

• The HFT is thin, unique, innovative and robust

• The designs have been tested extensively with hand calculations and more carefully with specific examples tested with GEANT/ITTF simulations

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The Pixel Detector lies beneath the SSD and IST

60Jim Thomas - LBL

Kinematic Mounts

• Kinematic mounts exploit the fact that three points define a plane

• Obvious ‘perfect’ alignment with four spheres 3 points of contact

• Reproducible position to 10 m, often used on optical benches

• More typical design on the right … the difficult part is to maintain enough pressure on the points of contact to hold their position

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Hinge and Cooling Duct detail

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Air Cooling

Silicon power: tested at 170 mW/cm2 (~ power of sunlight) 350 W total in the ladder region (Si + drivers)

computational fluid dynamics

Air-flow based cooling system for PXL to minimize material budget.

Detector mockup to study cooling efficiency

ladder region

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MSCPixel Insertion TubePixel Support Tube

IDSEast Support CylinderOuter Support CylinderWest Support Cylinder

PIT

PST

ESC

OSC

WSC

Shrouds

Middle Support Cylinder

Inner Detector Support

Structures: Exploded Detail

Assemble using bolted interfaces

MSC installed into IDS after IDS assembled (detectors not shown)

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Stability Performance

• IDS analyzed for deflection

• Anticipated response convolved with measured STAR vibration environment

• RMS Stability under 10 m

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East Pole Tip as seen during a summer shutdown

Beam-Beam counter installed in East Pole Tip

View of Existing East Pole Tip Area

66Jim Thomas - LBL

The Silicon Strip Detector – an existing detector

• 20 ladders located at a radius of 22 cm

• Double sided Si strips, 95 m pitch, 4 cm long, crossed at 35 mrad

• The electronics on each end of the ladder are to be upgraded

• Readout Goal: > 1 kHz for all detectors in the HFT